Filter



F. W. YOUNG Sept. 11, 1951 FILTER Filed June 4, 1947 2 Sheets-Sheet lull. l "al INVENTOR.

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Filed June 4, 1947 2 sheets-sheet 2 IN VEN TOR.

Patented Sept. 11, 1951 UNITED-Y PAT ENT OFFICE FILTER Y Frank W..Young,.Med=feld, Mass.

Application June 4, 1947, Serial No. 752:,468'

This invention vrelates to, continuousl vacuum iilterstofl thehorizontal rotary drum type wherein a compartmentalized iilter` surfaceis revolved through` a body of liquid containing suspended solids, thedrum being.v subjected to a vacuum whereby to facilitate the formationof a cake of the solids on the filter surface, theY cake beingdischarged from the drum by any suitable means, including usually ablowback or reverse pressure system.

More particularly, the inventionis concerned with -a continuous vacuumVfilter. having novel filter-fabric supporting and retaining means serv'-ing also to divide the lter drum surface into individual filtery cellsor compartments.

It has been common to cover the. surface of a filter, drum divided intocontiguous, compartments or cells with a filter medium. or: coverincluding a piece of cloth or wire. Afxationof the lter.

clothto the drum exterior has been achievedin a variety of ways, by, forexample, the use of a, spiral wirev winding, vor by rope. caulking, ofpjortions ofthe cloth in channels formedv in the filter oompartmental'divisions, or by fastening retaining strips in such channels usingscrews-or'by attaching a strip or rod on top of an ungrooved division,or by a combination of'l spiral wind-lngl with any other, of theforegoing. '1"0 prevent ex;- cessive bellying ofj the filter cloth inthe dischargearea when subjected to reverse pressure, spiral winding ofthe filter-fabric has ,often been thought necessary.

The use of spiralwire binding,or of other securing means presentingrelatively small areasof `high pressure contact between` the retainingmembers and thel filter cloth, substantially reduces the life of thelatterl by quickly wearing' holes at the points of Contact. Caulkingrenders non-productive a considerable area of otherwise available filtersurface and hasthe further disadvantage of being time-consuming in bothap plication and removal. More frequent shutdowns forV removing andreplacing worn fabric (i Claims. (Cl. 21d-199')` coverings where spiralwinding is used result, in

vby interference with complete dislodgement of the cake by the dischargemeans.

An object of the invention, therefore, is the` provision in a continuousvacuum drum filter of fabricretaining means whereby the filter cloth maybe held snugly about the drum surface-andiny spaced relation theretowithout the use of spiral wire winding.

Another object 0f the invention is to provide in' a continuous filter,filter-fabric retaining andi supporting means which will simultaneously`serve to dividethe cylindrical filter surface intolongitudinalcontiguous filter compartments sealed one from the other. f Stillanother object of the invention is to prolong the life of the filterfabric of a continuous vacuum filter by the provision-of improved non`Wearing fabric retaining means and thereby to reduce the frequency ofshutdowns for repair and replacement of the filter media.

A further object is the provision in a drum filter of novel filter-mediaretaining means which willv permit more perfect discharge of the cakefrom the filter surface.

With these and other objects in View, the invention ris featured by theprovision in a rotary drum type filter of a plurality of peripherallyspaced. members providing longitudinal parallelslots with narrowedopenings and dividing the filter surface into a number of contiguouscells or compartments running the length of the drum, the fabric filtercover being depressed into and heldin the slots or channels by means ofremovable locking rods or plugs.

Referring to the accompanying drawings,` inl which like numerals referto like parts in the several views,

Fig. 1 is a transverse section on a diameter of the continuous drumvacuum lter;

Fig; 2 is an enlarged View partly in perspective of a portion of thedrum surface, showing the fabric covering in place;

Fig'. 3- is an enlarged section of a portion of the drum showing indetail the novel fabric locking means;

Fig. 4 is a fragmentary sectional v iew of an en d of the drumVillustrating the manner of re' taining the sides of the lter Acloth bycaulking.

The filter drum I0 is rotatably mounted with its longitudinal axisdisposed horizontally and its `lower portion immersed in a tank or vatI2. The mounting and driving means, known andkv conventional in the art,form no part of the present invention and consequently are not shown inthe drawings.

The vat I 2- contains solids suspended in a liquid vehicle forming amixture I5 from which it is desired to extract them by filtration. rIhelevel of the mixture |4 in the vat is controlled by any suitable systemof inlet piping I6 and outlet valves and dams, shown at I8.

The filter drum I is of usual structure and includes a cylindricalsupporting metal body portion 20 mounted at each end of drum closures 22and having spaced about its entire periphery a series of ports 24communicating with its interior. By pumping means and associated piping25 the pressure inside drum I0 is maintained below that on the exterior,and by the pressure differential thus caused, the liquid vehicle of themixture |4 is forced through the hereinafter described filter media andthe ports 24 (as shown by arrows) into the drum I0 from which asfiltrate |5 it is removed through pipe 25, as shown by an arrow in Fig.1.

The pipe 25 may be disposed to maintain the filtrate at any desiredlevel within the drum for optimum results, as will hereinafter morefully appear.

As shown in Figs. 1 through 4, spaced about the entire outer surface ofthe drum are parallel longitudinally disposed slotted metallic tubes 26welded at 21 to the base 20 and dividing the surface thereof into filtercells or compartments each served by several of the ports 24. Thecylindrical tubes 26 open outwardly to form grooves provided with smoothnon-fraying edges 28 at either side of their narrowed mouths 30 byfolding the slot edges back upon themselves. Between the tubularcompartmental divisions 26 are held in place drainage bridges 32, havingperforations 33 through.

The lter fabric of wire or cloth 34 is held in place about the drum I0by tucking portions into the grooves or slots provided by the tubes 26and inserting from the slot ends removable retaining rods 36 to overliesuch portions, thereby sealing the filter compartments one from theother.

For example, in order to lock the cloth 34 in filtering position, theremovable bridges 32 are first slid endwise into place between the tubes26. A portion of the cloth near one end 40 thereof is then pressed downby means of a narrow smooth tool into an open throat of groove 30 in atube 26, and rod 36 is inserted over such tucked portion to anchor it inposition. The cloth is then stretched over anl intervening bridge 32 tothe next tubular division 26, where the locking is repeated. Theprocedure is continued until the entire cylindrical surface of the drumis covered with the snugly fltting filter cloth. It will be noted thatthe cloth will be automatically tensioned by the insertion of theretaining rods 36, since, by the use of a narrow flat tool, a foldinsufficient to accommodate the round rod is first depressed into theslot in the tucking operation. The subsequent insertion of thecylindrical rod pulls more fabric into the slot, thereby tensioning thecloth. Subsequently, slack, if any, may be taken up, one compartment ata time, by tensioning the cloth successively all the way around thedrum. The loose end is then locked in a slot 30 by rst-removing one ofthe rods 36 and tucking an end 38 on top of the end 40 and reinsertingthe rod. Where the cloth is .too long, as will often happen, the end 38may be locked in place and any excess fabric protruding from the slotthereafter trimmed back evenly.

To provide a seal at both ends of the drum I0, circumferential groovesor troughs 42 are cut in the edges of the steel body portions 20. Asshown most clearly in Fig. 4, the sides of filter fabric,34 are drawndown over the ends of the bridges 32 and depressed into the grooves 42.Hard sash cord 44, which swells when wet to lock more tightly, ispounded into the troughs 42 over the fabric as caulking, to retain thecloth firmly in position.

Discharge of the cake is accomplished by a blow-back system disposedwithin the drum, includinga chamber 46 and associated pipe 48. Portions5|! and 5|, forming :closures for the chamber 46, are arranged for aliquid seal fit with the interior surface of the drum I0. The cake 53deposited on the lter surface is subjected to a pressure differential,as shown by the arrows, tending to press it against the drum until, asthe drum revolves, it reaches the area designated at 52. Here portion5I) serves as a baffle to isolate the cake from further effect of thepartial vacuum within the drum. Further rotation of the drum moves thecake to a point opposite the opening 4'| of -chamber 46, to which issupplied air under greater than atmospheric pressure through pip-v ing48. This air, as shown by the arrow, is forced successively throughports 24 and perforations 33, and also through the filter cloth 34,effective-l ly dislodging vthe cake 53 and permitting it to drop freefrom the drum as loose pieces 55, or, depending on thenature of thecake, as a continuous sheet. Y

Within the chamber 46 an upward extension 54 of the baffle 5| restrictsthe opening 41 to approximately the width of a port 24, making moreeective the blow-back by the increased air velocity thus caused.

Leakage of air from chamber 46 around the baffles 56 and 5| is minimizedby a liquid seal as now described. Filtrate tends to flow downwardlyboth by gravity and rotation of the drum under the upper bailie 50, butthis tendency is counterbalanced by the existing air pressure,differential. Likewise the tendency of air to escape past baflle 5| iscounteracted by maintaining the levelof filtrate I5 above the bottom ofthebaiile 5| but below baffle 50 by means of exhaust pipe 25, thus alsoproviding a liquid seal in the area of thev lower baflie 5|.

It will be apparent that this novel construction and arrangement offilter parts enables the filter cloth to beheld in close-fittingrelationship to the external surface of the iilterdrum without the useof spiral wire winding or of caulking. The fabric may be pulled as tautas desired to prevent bellying'at'the discharge area and is readilylocked in place by the insertion of thel longitudinal rods. In likemanner removal and replacement of the cloth is facilitated by the use ofthe novel locking means.

While there is here disclosed a preferred embodiment, it is apparentthat changes and alterations maybe made-without departing from thespirit and scope of the invention.

I claim: Y

1. In a filter, filter media comprising, in combination, a supportingvbase, tubular division strips each aflixed along a narrow longitudinalarea thereof to said base and dividing the same into contiguous filtercompartments each pro-A and having spacedA narrow.y parallel portions,

thereof depressed into said grooves, and retaining rods fitting said.grooves to overlie and retain said portions to lock said lter fabric ineffective filtering position.

2. In a lter, lter media comprising, in combination, a supporting basehaving spaced ports therein, tubular division strips each affixed alonga narrow longitudinal area thereof to said base to divide the same intocontiguous filter compartments each drained by at least one of saidports, said strips being slotted to provide outwardly facing grooveswith narrowed openings, perforated bridges having depending flanges onthe sides thereof, said bridges being adapted to be slid between and toengage said strips and to be held in operative position on said base bythe engagement of said flanges with said tubular strips, filter fabriccovering said compartments, supported by said bridges and having spacednarrow parallel portions thereof depressed into said grooves, andretaining rods fitting said grooves to overlie and retain said portionsto lock said filter fabric in effective filtering position.

3. In a filter, lter media comprising, in cornbination, a supportingbase having spaced ports therein, tubular division strips each affixedalong a narrow longitudinal area thereof to said base to divide the sameinto contiguous lter compartments each drained by at least one of saidports, said strips being slotted to provide outwardly facing grooveswilth narrowed openings, perforated bridges having depending perforatedflanges on the sides and ends thereof, said bridges being adapted to beslid between and to engage said strips and to be held in spaced relationto and in operative position on said base by the engagement of said sideflanges with said strips, lter fabric covering said compartments,supported by said bridges and having spaced narrow parallel portionsthereof depressed into said grooves, and retaining rods fitting saidgrooves to overlie and retain said portions to lock said filter fabricin effective filtering position.

4. In a filter, filter media comprising, in combination, a supportingbase, tubular division strips each affixed along a narrow longitudinalarea thereof to said base and dividing the same into contiguous filtercompartments, said compartments being provided with drains, saiddivision strips being slotted to provide outwardly facing grooves withnarrowed openings, and perforated bridges fitting said compartments andhaving depending longitudinally extending anges on the sides thereof,said bridges being held by said flanges between and in engagement withsaid strips and in spaced relation to said base, said compartments beingadapted to be covered by filter fabric supported by said bridges andheld in effective ltering position by having spaced narrow parallelportions thereof depressed in said grooves and retained therein by rodsfitting said grooves and overlying said portions.

5. In a filter, lter media comprising, in combination, a supportingbase, metallic tubular division strips each welded along a narrowlongitudinal area thereof to said base and dividing the latter intocontiguous filter compartments sealed one from the other, saidcompartments being provided with drains, said division strips beingslotted to provide outwardly facing grooves with narrowed openingshaving smooth non-fraying edges, and perforated bridges fitting saidcompartments and having depending longitudinally extending perforatedflanges on the sides thereof, said bridges being supported in spacedrelation to said base by the engagement therewith of the edges of saidflanges and further being held against outward movement by the lockedengagement of the sides of said anges with said strips, saidcompartments being adapted to be covered by filter fabric supported bysaid bridges and held in effective filtering position by having spacednarrow parallel portions thereof depressed in said grooves and retainedtherein by rods fitting said grooves and overlying said portions.

6. In a filter, lter media comprising, in combination, a supportingbase, a series of division strips each having a generally cylindricalouter surface and being affixed along a narrow longitudinal area of saidsurface to said base so that portions of said surface overhang said baseon both sides of said strip, said strips dividing said base intocontiguous filter compartments sealed one from the other, saidcompartments being provided with drains, and perforated bridges ttingsaid compartments and having depending longitudinally extendingperforated flanges on the sides thereof, said bridges being supported onand in spaced relation to said base by said flanges while being heldagainst outward movement by Y the locked engagement of the sides of saidflanges with said overhanging portions of said strips.

FRANK W. YOUNG.

REFERENCES CITED The following references are of record in the le ofthis patent:

UNITED STATES PATENTS Number Name Date 1,892,306 Hillier Dec. 27, 19322,134,703 Cobb Nov. 1, 1938 2,204,928 C'ulver June 18, 1940 2,289,411Denhard et al July 14. 1942

